Method and system for classifying image elements

Abstract

A method, system, and machine-readable medium for classifying an image element as one of a plurality of categories, including assigning the image element based on a ratio between an unoccluded perimeter of the image element and an occluded perimeter of the image element and coding the image element according to a coding scheme associated with the category to which the image element is classified. Exemplary applications include image compression, where categories include image foreground and background layers.

What is claimed is: 
     
       1. A method comprising:
 identifying a first image element of an image as a background and a second image element of the image as a foreground; and 
 encoding, via a processor, the first image element using a number of bits that is proportional to a length of un-occluded perimeter segments of the first image element relative to a length of occluded perimeter segments of the first image element that result from occlusions by foreground elements of the second image element. 
 
     
     
       2. The method of  claim 1 , wherein the number of bits used for encoding the first image element is reduced by excluding occluded parts of the first image element. 
     
     
       3. The method of  claim 1 , wherein edges of the first image element are at least partly defined by boundaries of the second image element. 
     
     
       4. The method of  claim 1 , further comprising:
 processing, via the processor, the image based on a relative occlusion between the first image element and the second image element, wherein the relative occlusion is determined using a color difference between the first image element and the second image element. 
 
     
     
       5. The method of  claim 4 , wherein the color difference is calculated using a color differential between the first image element and the second image element. 
     
     
       6. The method of  claim 4 , wherein the background is assigned to an occlusion category based on the relative occlusion meeting a threshold. 
     
     
       7. The method of  claim 1 , wherein the number of bits used for encoding the first image element is selected based on a proportionality coefficient that depends on color differences along an element boundary of the first image element. 
     
     
       8. A system comprising:
 a processor; and 
 a computer-readable storage medium having instructions stored which, when executed by the processor, cause the processor to perform operations comprising: 
 identifying a first image element of an image as a background and a second image element of the image as a foreground; and 
 encoding, via a processor, the first image element using a number of bits that is proportional to a length of un-occluded perimeter segments of the first image element relative to a length of occluded perimeter segments of the first image element that result from occlusions by foreground elements of the second image element. 
 
     
     
       9. The system of  claim 8 , wherein the number of bits used for encoding the first image element is reduced by excluding occluded parts of the first image element. 
     
     
       10. The system of  claim 8 , wherein edges of the first image element are at least partly defined by boundaries of the second image element. 
     
     
       11. The system of  claim 8 , wherein the computer-readable storage medium stores additional instructions which, when executed by the processor, cause the processor to perform operations further comprising:
 processing the image based on a relative occlusion between the first image element and the second image element, wherein the relative occlusion is determined using a color difference between the first image element and the second image element. 
 
     
     
       12. The system of  claim 11 , wherein the color difference is calculated using a color differential between the first image element and the second image element. 
     
     
       13. The system of  claim 11 , wherein the background is assigned to an occlusion category based on the relative occlusion meeting a threshold. 
     
     
       14. The System of  claim 8 , wherein the number of bits used for encoding the first image element is selected based on a proportionality coefficient that depends on color differences along an element boundary of the first image element. 
     
     
       15. A computer-readable storage device having instructions stored which, when executed by a computing device, cause the computing device to perform operations comprising:
 identifying a first image element of an image as a background and a second image element of the image as a foreground; and 
 encoding, via a processor, the first image element using a number of bits that is proportional to a length of un-occluded perimeter segments of the first image element relative to a length of occluded perimeter segments of the first image element that result from occlusions by foreground elements of the second image element. 
 
     
     
       16. The computer-readable storage device of  claim 15 , wherein the number of bits used for encoding the first image element is reduced by excluding occluded parts of the first image element. 
     
     
       17. The computer-readable storage device of  claim 15 , wherein the number of bits used for encoding the first image element is selected based on a proportionality coefficient that depends on color differences along an element boundary of the first image element. 
     
     
       18. The computer-readable storage device of  claim 15 , wherein the computer-readable storage device stores further instructions for controlling the processor to perform further operations comprising:
 processing the image based on a relative occlusion between the first image element and the second image element, wherein the relative occlusion is determined using a color difference between the first image element and the second image element. 
 
     
     
       19. The computer-readable storage device of  claim 18 , wherein the color difference is calculated using a color differential between the first image element and the second image element. 
     
     
       20. The computer-readable storage device of  claim 18 , wherein the background is assigned to an occlusion category based on the relative occlusion meeting a threshold.